This invention relates to rock crushing systems, such as conical rock crushers or gyratory crushers. Specifically, this invention elates to the main shaft assembly and head nut system.
Gyratory rock crushers generally have a downwardly expanding central conical member which rotates or gyrates within an outer upwardly expanding frustroconically shaped member typically called a shell. The shell can be comprised of two or more pieces, e.g., a top shell and a bottom shell. The central conical member generally has a wearing cover or a liner called a mantle. A spider assembly rests on the top shell, forming the top of the support structure for the machine.
A shaft extends vertically through the rock crusher. This shaft is supported by a bearing in the spider assembly. The central portion of the shaft tapers inwardly in an upward direction to form the central conical crushing member. This portion of the shaft supports the mantle, which moves with the shaft to effect the crushing operation. The spider assembly is designed to support the shaft while allowing gyratory movement during operation of the machine. Additionally, the vertical position of the shaft is controlled by a piston arrangement in the spider.
A head nut, attached to a sleeve disposed about the shaft is used to retain the mantle in place. The head nut resists upward forces from the mantle, which tends to move in an upward direction during crusher operation. The head nut is also subject to wear from the operation of the machine, as well as damage from impacts due to the rocks being dumped into the machine from above. The head nut is disposable, but the threads used to secure the head nut to the shaft may become damaged as well. If the threads are stressed out of shape due to operation, suffer fatigue failures such as cracking of the threads, or are damaged due to impacts from falling material on the head nut, repairs can be expensive. Repairing damaged threads on the shaft may include removing the shaft from the machine to be refurbished. The repair operation is costly both because of the cost of reworking the shaft as well as the cost of machine down time while the shaft is being repaired. Accordingly, the crushing system is designed so that the shaft of the crusher is preserved from being repaired in favor of other components which may be more easily repaired or replaced, such as a sleeve.
A design that does not require threads on the shaft results in a smooth shaft with a resultant lower incidence of failure. Sleeves are sometimes used between the shaft and the head nut to avoid the use of threads directly on the shaft, but the sleeves may require complicated arrangements to be secured in a vertical direction with respect to the shaft. Also, split sleeves that are sometimes used require fasteners for installation. Preferably, the sleeve and head nut are compact and replaceable in case of damage or maintenance needs. The presence of additional fasteners on the sleeve or head nut complicates assembly, removal, and maintenance.
Therefore, it would be advantageous to have a sleeve and head nut arrangement that does not require threads on the shaft. Further, there is a need for a head nut assembly that is self-tightening in response to upward loads. Further still, there is a need for a compact and easily replaceable sleeve and head nut arrangement that does not require additional fasteners.
An exemplary embodiment relates to an attachment apparatus for a gyratory crusher including a shaft and a mantle disposed about the shaft. The attachment apparatus has a sleeve disposed about the shaft defining a contact surface between the sleeve and the shaft and a head nut threaded onto the sleeve. The radius of the shaft increases in an upward direction over at least part of the contact surface, whereby the head nut retains the mantle with respect to the shaft in at least one direction.
Another embodiment relates to an attachment apparatus for a gyratory crusher including a shaft and a mantle disposed about the shaft. The attachment apparatus has a sleeve disposed about the shaft and a head nut threaded onto the sleeve. The sleeve is a continuous ring, whereby the head nut prevents upward motion of the mantle.
Still another embodiment relates to a gyratory crusher having a shell, a shaft disposed within the shell, a mantle covering a portion of the shaft, a head nut located above the mantle, and a sleeve between the head nut and the shaft. The sleeve is maintained and positioned on the shaft by means of a tapered contact surface between the sleeve and the shaft.
A still further embodiment relates to a method of assembling or repairing a gyratory crusher. This method includes heating a sleeve, placing the sleeve over a shaft, cooling the sleeve to effect a shrink fit arrangement on the shaft, and threading a head nut onto the sleeve.